Finding a sentence and a graph model

[sara15]

can we define a V-sentence phi such that phi has arbitrarily large finite models and , for any finite model G , |G| is even . and then finding a finite graph G such that |G| is even and G doesnot model the sentence phi that I mentioned above.
please explain it to me

 

[AKG]

Hint: For every finite graph, the number of its vertices which have odd degree is even.
Hint for Proof of Hint: Induction on the number of edges.